Ethnic differences in pain perception is a research topic of substantial basic science and clinical import. Several laboratory studies, conducted by ourselves and other researchers, provide evidence of ethnic differences in responses to experimental pain. However, the consistency and magnitude of these effects are quite variable, and the factors mediating ethnic differences in pain perception have not been investigated. The studies proposed in this application are designed to further elucidate the nature and mechanisms of ethnic differences in pain responses by investigating perceptual and physiological responses to experimental pain stimuli in African Americans, Hispanic Americans and non-Hispanic whites. Four clinically relevant laboratory pain induction procedures will be used in these studies: thermal pain, mechanical pressure pain, ischemic pain, and cold pressor pain. Multiple dimensions of the pain experience will be assessed, including pain threshold and tolerance, sensory and affective ratings of pain, and temporal summation of thermal pain. In addition, cardiovascular and neuroendocrine (cortisol and beta-endorphin) responses to the pain tasks will be measured. Psychologic and sociocultural variables that may influence pain responses will also be assessed, and mediational analyses will be performed to elucidate the factors contributing to ethnic differences in pain sensitivity. It is hypothesized that: 1) African Americans and Hispanic Americans will exhibit greater pain sensitivity than non-Hispanic whites; 2) psychological and sociocultural variables such as coping style, pain-related expectancies, negative affect, ethnic identity, and cultural beliefs about pain will differ among the ethnic groups and will partially mediate group differences in pain perception; 3) non-Hispanic whites will show greater cardiovascular, cortisol and beta-endorphin responses to pain. Structural equation modeling will be performed to examine interactions among sociocultural, psychosocial and physiological variables that may explain ethnic differences in pain perception. The results of this research will provide unique and important information regarding ethnic differences in pain responses.